Mineral wool insulation

ABSTRACT

A method of manufacturing a mineral fibre thermal insulation product comprises the sequential steps of:
         Forming mineral fibres from a molten mineral mixture;   Spraying a substantially formaldehyde free binder solution on to the mineral fibres, the binder solution comprising: a reducing sugar, an acid precursor derivable from an inorganic salt and a source of nitrogen;   Collecting the mineral fibres to which the binder solution has been applied to form a batt of mineral fibres; and   Curing the batt comprising the mineral fibres and the binder which is in contact with the mineral fibres by passing the batt through a curing oven so as to provide a batt of mineral fibres held together by a substantially water insoluble cured binder.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.12/671,922, filed Apr. 15, 2011, which is a U.S. national counterpartapplication of International Application Serial No. PCT/EP2008/060178,filed Aug. 1, 2008 under 35 U.S.C. § 371, which claims priority to GBPatent Application Serial Number 0715100.4, filed Aug. 3, 2007, GBPatent Application Serial Number 0807777.8, filed Apr. 29, 2008, and GBPatent Application Serial Number 0810297.2, filed Jun. 6, 2008, theentire disclosure of each of which is hereby incorporated herein byreference.

TECHNICAL FIELD

This invention relates to the manufacture of mineral wool insulation,for example glass wool or stone wool insulation, and to mineral woolinsulation products.

BACKGROUND

WO 2007/014236 (incorporated herein by reference) discloses manufactureof mineral wool insulation products using binders which compriseMaillard reactants. One particular binder disclosed is based on atriammonium citrate-dextrose system derived from mixing dextrosemonohydrate, anhydrous citric acid, water and aqueous ammonia. One ofthe many advantages of this binder system is that it is formaldehydefree.

SUMMARY

One aspect of the present invention provides a method of manufacturing amineral fibre thermal insulation product in accordance with claim 1;further aspects of the inventions are defined in other independentclaims. The dependent claims define alternative and/or preferredembodiments.

Binder solutions used in accordance with the present invention may be“substantially formaldehyde free”, that is to say that they liberateless than 5 ppm formaldehyde as a result of drying and/or curing (orappropriate tests simulating drying and/or curing). Such bindersolutions are preferably “formaldehyde free”, that is the say theyliberate less than 1 ppm formaldehyde in such conditions.

Insulation materials in accordance with the invention which incorporatebinders may be “substantially formaldehyde free”, that is to say thatthey comprise less than 5 ppm or less than detectable limits of freeformaldehyde and/or consist of materials which together comprise lessthan these amounts of free formaldehyde and/or release levels offormaldehyde in standardised tests adapted to simulate their ordinaryuse which allows them to be classified as having no or undetectablelevels of formaldehyde release. Preferably, such products release lessthan 10 μg/m³, more preferably less than 5 μg/m³ of formaldehyde duringthe period of 24-48 hours from the start of testing in accordance withISO 16000.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a plan view of a mineral fibre test sample, where r isradius=12.7 mm, DC is distance between centers=44.5 mm, a=25.4 mm, andb=121 mm.

DETAILED DESCRIPTION

It has been found that insulation materials made according to thepresent invention may have at least equivalent and indeed improvedproperties compared to, for example, products made using thetri-ammonium citrate-dextrose system of WO 2007/014236. WO 2007/014236teaches binder systems based, inter alia, on a combination of acarbohydrate (for example a reducing sugar), ammonia and a carboxylicacid and suggests that a Maillard type reaction may form the basis ofthe curing chemistry. It would have been thought that the nature of theacid used would have a significant effect upon the properties of thecured binder, particularly if the acid precursor and/or a derivativetherefrom is incorporated into the structure of the cured binder. It isthus surprising that an acid precursor derivable from an inorganic saltshould provide a suitable acid precursor in an otherwise apparentlysimilar binder system.

Use of an acid precursor derivable from an inorganic salt may havesignificant advantages in terms of cost, availability and ease ofhandling. A particular advantage can be achieved by use of one or moreinorganic ammonium salts, for example, an ammonium sulphate, an ammoniumphosphate or an ammonium carbonate. An ammonium salt may provide the orpart of the acid precursor and/or the or part of the source of nitrogenand/or the or part of a pH control system. An ammonium nitrate may alsowork; however, ammonium nitrate may oxidise aldehyde groups of thecarbohydrate (for example in the case of dextrose) and/or requireprecautions to avoid explosions.

An ammonium sulphate is particularly advantageous but ammonium phosphatemay be used in addition to or instead of this. Ammonium phosphate may bemono ammonium phosphate, di ammonium phosphate or tri ammoniumphosphate; it may be an ammonium hydrogen phosphate. An ammoniumcarbonate, alone or in combination with the other materials disclosedherein, may also provide good results. The ammonium carbonate may be anammonium bicarbonate.

The acid precursor, particularly when this consists essentially ofinorganic ammonium salt(s), may make up

-   -   at least 5%, preferably at least 7%, more preferably at least 9%        by dry weight of the uncured binder solution; and/or    -   less than 20%, preferably less than 18%, more preferably less        than 16% by dry weight of the uncured binder solution.

The acid may comprise: a sulphuric acid, a phosphoric acid, a nitricacid or a weak acid.

The binder may comprise between 5%-25%, preferably 10% to 20%, morepreferably 15% to 20% by dry weight of acid precursor (particularlywhere this is an inorganic ammonium salt) to carbohydrate (particularlywhen this is a sugar).

Where the binder comprises both an acid precursor derivable from aninorganic salt and an organic acid with the carbohydrate (particularlywhere this is a sugar), these may be present in the following amounts bydry weight with respect to the carbohydrate:

Preferred More preferred Most preferred acid precursor At least 2.5% Atleast 5% derivable from an inorganic salt organic acid At least 2.5% Atleast 5% Combination of 5-25% 10-20% 15-20% organic acid and acidprecursor derivable from an inorganic salt

Where an organic acid is used, this is preferably derived from anammonium salt. For example, an ammonium citrate, particularlytri-ammonium citrate may be used as a source of citric acid.

Prior art phenol formaldehyde binder systems for mineral wool insulationhave been used with the addition of about 2% by weight ammonium sulphateas a curing agent. However, the chemistry of such phenol formaldehydebinder systems is not comparable to the binder systems of the presentinvention which are not based on phenol and/or formaldehyde and/or onother phenolics.

A carbohydrate may be used in the binder solution rather thanspecifically a reducing sugar and may comprise a monosaccharide, forexample in its aldose or ketose form. Preferably, the carbohydratecomprises a sugar, more preferably a reducing sugar or a reactant thatyields a reducing sugar in situ under thermal curing condition; it maycomprise glucose (ie dextrose). The carbohydrate may comprise acarbohydrate having a reducing aldehyde. It is believed that the use ofa reducing sugar and particularly dextrose gives particularly goodresults for the manufacture of mineral wool insulation products. Thedextrose need not be 100% pure but use of a material having a dextroseequivalent value of at least 0.85, preferably at least 0.9 and morepreferably at least 0.95 is thought to be advantageous. The dextroseequivalent value DE can be thought of as i) a measure ofde-polymerization and is roughly: DE=100/dp where dp stands for degreeof polymerization or ii) the total amount of reducing sugars calculatedas D-glucose (dextrose) on a dry basis.

Preferably, the binder solution and/or the binder is free orsubstantially free of starch; the presence of substantial quantities ofstarch is thought to increase the curing time and/or reduce the strengthof the cured binder. The binder solution and/or the binder may be freeor substantially free of proteins.

Industrial, non-food grade dextrose may be used as the reducing sugar,products such as Sirodex331 which is a 75% solids sugar solutionobtainable from Tate and Lyle with a DE value of 94.5 may be used.

Particularly in the case where the reducing sugar consists essentiallyof dextrose and the acid precursor consists essentially of an ammoniumsalt, for example an ammonium sulphate, the ratio by dry weight of theamount of reducing sugar/the amount of acid precursor may be greaterthan or equal to 2.5 and/or less than or equal to 13.

The source of nitrogen may be an amine or an amine reactant; it may bederivable from the same source as the acid precursor, for example, froman inorganic ammonium salt. It is preferably ammonia in solution.

Precursors for and/or reactants which give the materials referred to maybe used.

In one embodiment, the binder is derived essentially from a reducingsugar and an inorganic ammonium salt in aqueous solution.

In another embodiment, the binder may also comprise an organic acid,particularly a carboxylic acid; this may be a polycarboxylic acid,particularly a bi-carboxylic acid or tri-carboxylic acid, preferablycitric acid; it is preferably monomeric. The combination of an organicacid (or a precursor a salt or an anhydride thereof) with an acidprecursor derivable from an inorganic salt may present variousadvantages. Firstly, such a combination may reduce the risk of punking(which has been observed with such binders based solely on organicacids) whilst providing acceptable strength. Punking is a term of art inthe mineral fibre insulation area which generally denotes acomparatively rapid oxidation of a binder with a concomitant generationof heat in a finished and generally packaged insulation product. Punkinggenerally causes generation of fumes and discolouring of the insulationmaterial. It may be associated with exothermic reactions which increasethe temperatures through the thickness of the insulation material; thismay destroy the integrity of the insulation product and/or present afire hazard.

Alternatively or additionally, the combination of an organic acid (or aprecursor, a salt or an anhydride thereof) with an acid precursorderivable from an inorganic salt may moderate acid conditions occurringduring curing and thus reduce the risk or tendency of such conditions tocause significant damage to the material being bound. Such a combinationmay be particularly advantageous as a binder for stone wool insulationwhose fibres may be more susceptible to potential damage by acid than,for example, glass wool insulation.

In a further embodiment, the binder is derived essentially from: acarbohydrate; an inorganic ammonium salt; and an organic acid and/ororganic acid precursor; in aqueous solution.

The term “consist or consisting essentially of” is intended to limit thescope of a claim to the specified materials or steps and those that donot materially affect the basic and novel characteristic(s) of theclaimed invention.

Binders which comprise or consist essentially of the componentsdescribed herein may include additives, for example, additives selectedfrom: silanes, mineral oils, coupling agents, silicones or siloxanes(particularly for water repellency), silicon containing compounds,surfactants, hydrophilic additives, hydrophobic additives, waxes,substances useful for controlling the pH (e.g. ammonium hydroxide) andammonia. Ammonium hydroxide when used, and indeed other additives, mayprovide the and/or an additional source of nitrogen. Preferably, thetotal quantity of additives (excluding ammonia) is less than 5% byweight (excluding the weight of water present), more preferably lessthan 3% or less than 2% by weight.

It is preferred to include a silane as an additive. The binder and/orbinder solution may comprise at least 0.1% and/or less than 1% of asilane by dry weight. The silane may be amino substituted; it may be asilyl ether and it is believed that its presence may significantlyimprove the long term strength of the binder, particularly afterweathering.

Preferences for the pH of the binder are:

Preferred More preferred Most preferred pH of binder ≥7 ≥8 ≥9at least in the state in which the binder is applied to a material to bebound and/or recovered in a waste water recuperation system. Such aneutral or alkaline pH of the binder may alleviate problems of corrosionof manufacturing equipment which have been encountered with someessentially acidic prior art binder systems. Such prior art bindersinclude binders consisting essentially of polyacrylic acids or polymerpolycarboxylic acids. One particular advantage of the present inventionis thus the use of a binder system that can operate in such neutral oralkaline conditions. When cured, the binder may become acidic during thecuring process. However, equipment corrosion considerations are lesssignificant in this case due to the minimal contact between themanufacturing equipment and the binder when in this state. The pH of thebinder may be less than or equal to 13, preferably less than or equal to12, 11 or 10. A preferred pH may be in the range of 7.5 to 9.5,particularly 8 to 9.

It is preferred to arrange the pH of the binder solution at anappropriate level to prevent precipitation of its constituents andparticularly to ensure that the acid precursor derivable from aninorganic salt remains in solution. This is particularly the case whereammonium phosphate provides the acid precursor. Better dry and/orweathered strengths and/or more homogeneous products may be achieved byusing homogeneous binder solutions comprising ammonium salt acidprecursors which are free from precipitates, particularly when ammoniumphosphate is used and the binder solution is free from phosphateprecipitates.

The binder composition may be provided in the form of an aqueoussolution; it may contain free ammonia or excess ammonia in solution. Aneutral or alkaline pH of the binder may be generated by an excess ofalkaline groups compared with acid groups present in the bindersolution, for example, due partially or substantially to the presence ofammonia in the solution. Additional ammonia may be added to the bindersolution, for example 0.2%-1% by weight, or indeed more; this may helpto keep a wash water system used in the manufacture of mineral woolinsulation alkaline over the long term.

When binder solution is sprayed on to hot mineral wool fibres just afterthey have been formed, the residual heat of the mineral wool fibres maycause a significant portion of any water in the binder solution toevaporate. Consequently, the mineral wool fibres which are thencollected to form a batt may have binder present on them in the form ofa sticky, viscous or tacky liquid. This may facilitate bonding betweenindividual fibres via the binder.

One of the many advantages of this binder system is that it is sprayedonto the mineral wool fibers in a substantially unreacted state. Theability to spray the binder solution onto the mineral wool fibers in asubstantially unreacted state may alleviate problems associated withpre-reacting the binder components in solution which have beenencountered with some prior art binder systems in which the componentsare pre-reacted. Such prior art binders include binders consistingessentially of pre-reacted polymers or resins which are applied to thematerials to be bound. With substantially unreacted binder present onthe mineral wool fibers in the form of a sticky, viscous or tackyliquid, the reaction between the binder components may occur in asubstantially dry state. One may describe the reaction as a bulkpolymerization because it is occurring without the benefit of a solvent.A particular advantage of the present invention is thus the use of abinder system that can polymerise in a substantially dry state orthrough a bulk polymerisation.

The mineral fibres may be formed by internal or external spinning. Theymay have a temperature in the range 20° C. to 200° C., generally 30° C.to 100° C. or 150° C., when sprayed with the binder solution. Thequantity of binder solution sprayed may be used with or withoutadditional water sprays to assist in cooling the mineral fibres to adesired temperature between their formation and their collection to forma batt.

A particular advantage of using ammonia in solution to control the pH ofthe binder solution applied to the mineral fibres is that at least partof the ammonia of binder solution that sticks to the fibres may flashoff due to the residual heat of the mineral wool fibres. Consequently,the binder solution that coats the fibres may have a lower pH than thebinder solution sprayed.

The binder may be curable; it may be cured, for example in a curingoven; it may form a thermoset binder. In its cured form, the binder may:comprise melanoidins; and/or be thermoset; and/or be water insoluble orsubstantially water insoluble. The binder solution may be substantiallycolourless or white to off-white; upon curing, the binder may take on adark colour, particularly a dark brown colour. The cured product may bedark in colour, particularly dark brown in colour. The binder may befree of proteins; it may be free of cellulosic feedstock. One of themany advantages of this binder system is that the extent of curing canbe determined by the colour. Substantially dehydrated binder appearswhite or off-white. Progressively cured to a greater extent, the binderappears progressively darker in colour (a darker shade of brown). Whenapplied to mineral fibers, the extent to which the mineral woolinsulation has cured can be determined by its colour.

When applied to the mineral fibres and/or prior to passing through thecuring oven, the binder may be free or substantially free of melanoidinsand/or other reaction products derived from curing. Curing of the bindermay produce glucosylamine, particularly as an intermediate product.Consequently, a cured or particularly a partially cured product maycomprise glucosylamine.

The reaction of the binder upon curing may be essentially a Maillardtype reaction as described for example in US Patent Application20070027283 or WO2007/14236. The binder may comprise polymerisationproducts of a mixture that comprises a reducing sugar and a materialselected from the group consisting of ammonium sulphate, ammoniumphosphate, ammonium nitrate and ammonium carbonate.

The binder solution may be formulated by combining:

-   -   A carbohydrate, preferably a reducing sugar;    -   An acid precursor derivable from an inorganic salt, preferably        an ammonium sulphate or ammonium phosphate;    -   A source of nitrogen; and    -   water.

The formulation may comprise optional or additional ammonia provided inthe form of an aqueous ammonia solution. The water may comprise washwater.

Forming the binder solution from a carbohydrate and an acid precursorcomprising an inorganic ammonium salt provides one particularadvantageous preparation method. This may be achieved in a simple mixingchamber which may be open and/or at atmospheric pressure. Thecarbohydrate and/or the acid precursor may be added in powder or liquidform. The preparation is preferably carried out at room temperature.Preferably it is not necessary to supply heat to prepare the bindersolution; nevertheless, the binder solution may be heated during itspreparation, for example to a temperature with the range 20° C. to 80°C., particularly where this facilitates dissolving and/or mixing of itsingredients.

The binder solution may comprise:

-   -   at least 5% 10%, 15% or 18% solids and/or    -   less than 50%, 40% or 20% solids        particularly determined as bake out solids by weight after        drying at 140° C. for 2 hours.

The binder solution and/or the binder are preferably organic.

The mineral fibre insulation may be shaped and/or dimensioned and/ormoulded with the aid of the binder.

The binder solution, particularly when applied to the mineral fibres,may have a viscosity appropriate for application by spraying or pouring.Its viscosity at 20° C. may be:

-   -   Less than about 1.5 Pa·s, preferably less than about 1×10⁻²        Pa·s; and/or    -   Greater that about 2×10⁻⁴ Pa·s, preferably greater than about        5×10⁻⁴ Pa·s

Curing of the binder may occur in a curing oven, for example usingforced hot air circulation; it may occur in a press. Curing may comprisea dehydration of the binder; it may comprise a polymerisation. Curingmay comprise a bulk polymerisation reaction. Curing may be carried outfor duration of 20 minutes or less, preferably 10 minutes or less.Curing of the binder preferably occurs when the binder solution (fromwhich water may have been evaporated) is in contact with the mineralfibres; it may occur at substantially atmospheric pressure. The curingmay be a substantially dry curing, that is to say by application of dryheat and/or substantially dry or heated atmospheric air rather thanusing steam or heated water vapour.

The curing temperature and time may be selected as a function of theproduct density and/or thickness. The curing oven in such cases may havea plurality of heating zones having temperatures within the range 200°C. to 350° C. (typically 230° C. to 300° C.). A thin, low densityproduct (12 kg/m³ or less) may be cured by passing through the curingoven in as little as 20 seconds; a thick, high density product (80 kg/m³or more) may require a passage of 15 minutes or more in the curing oven.The product may reach a temperature in the range 180° C.-220° C. duringthe curing process.

The cured binder may comprise greater than 2% and/or less than 8%nitrogen by mass as determined by elemental analysis.

The binder in its uncured state may comprise the following levels ofsulphates, phosphates carbonates and/or nitrates by dry weight:

-   -   Greater than 2.5%, 3% or 5%; and/or    -   Less than 25%, 22%, or 20%

Finished materials manufactured using binder systems according to thepresent invention may have residual levels of sulphates, phosphates,carbonates and/or nitrates derived notably from the inorganic saltserving as the acid precursor. Such species may be present in thefollowing quantities:

-   -   Greater than 500, 750, 1000 or 1500 mg/kg; and/or    -   Less than 5000, 4000 or 3000 mg/kg.

The presence of such species may be assessed in a leach test and providean indication in the final product of the binder system used.

The quantity of binder in the finished product may be:

-   -   Greater than: 1%, 2%, 2.5%, 3%, 3.5% or 4%; and/or    -   Less than: 20%, 15%, 10% or 8%        measured by dry weight of the finished product.

The mineral wool insulation may have one or more of the followingparting strengths: Ordinary Parting Strength of

-   -   At least 120 g/g, preferably at least 150 g/g; and/or    -   Less than 400 g/g

Weathered Parting Strength of

-   -   At least 120 g/g, preferably at least 150 g/g; and/or    -   Less than 400 g/g

% loss between Ordinary and Weathered Parting Strength of

-   -   Less than 10%, preferably less than 5%

The mineral wool insulation may have one or more of the followingcharacteristics:

-   -   A density greater than 5, 8 or 10 kg/m³;    -   A density less than 200, 180 or 150 km/m³    -   Comprise glass wool fibres and have a density greater than 5, 8        or 10 kg/m and/or less than 80, 60 or 50 kg/m³;    -   Comprise stone wool fibres and have a density greater than 15,        20 or 25 kg/m³ and/or less than 220, 200 or 180 kg/m³;    -   A thermal conductivity λ of less than 0.05 W/mK and/or greater        than 0.02 W/mK    -   Comprise less than 99% by weight and/or more than 80% by weight        mineral fibres.    -   A thickness of greater than 10 mm, 15 mm or 20 mm and/or less        than 400 mm, 350 mm or 300 mm.

Embodiments of the invention will now be described by way of examplewith reference to FIG. 1 which is a plan view of a test sample.

Shell Bone Testing:

Binders were prepared as aqueous solutions by

-   -   combining the ingredients of a desired binder formulation in an        open, unheated reaction vessel    -   adding distilled water    -   subsequently adding a silane solution    -   agitating during addition of liquids and afterwards for several        minutes to achieve complete dissolution of solids        such that the binder solution contained approximately 45%        dissolved solids as a percentage of total weight of solution. A        2-g sample of this solution, upon thermal curing at about        200° C. to 210° C. for 8 minutes, would yield 30% solids (the        weight loss being attributed to dehydration during thermoset        binder formation).

An evaluation of dry and “weathered” tensile strength of glassbead-containing shell bones provided an indication of the likely tensilestrength and the likely durability of fibreglass insulation or othermaterials prepared with that particular binder. Predicted durability isbased on the ratio of a shell bone's weathered tensile strength to itsdry tensile strength.

To prepare the shell bones, an electric mixer was used for about twominutes to mix approximately 75 g of binder with 727.5 g of glass beads(equivalent to Quality Ballotini Impact Beads, Spec. AD, US Sieve70-140, 106-212 micron-#7, from Potters Industries, Inc.). Any clumpsfrom the sides of the mixer whisk and from the sides and bottom of themixing bowl were mixed in manually using a spatula about halfway throughthe mixing and also at the end of the mixing.

The prepared glass beads/binder mixture was added to the mould cavitiesof a shell bone mould (Dietert Foundry Testing Equipment; Heated ShellCuring Accessory, Model 366) which had been pre-heated to about 218° C.(425° F.). The surface of the mixture in each cavity was flattened out,while scraping off the excess mixture to give a uniform surface area tothe shell bone. Any inconsistencies or gaps that existed in any of thecavities were filled in with additional glass beads/binder mixture andthen flattened out. The top platen was quickly placed onto the bottomplaten (to avoid producing shell bones with two differentially curedlayers). The cured shell bones were removed after seven minutes, cooledto room temperature on a wire rack, labelled and placed individually inplastic storage bags. If shell bones could not be tested on the day theywere prepared, the shell bone-containing plastic bags were placed in adessiccator unit. During curing the temperature of the bottom platenranged from about 204° C. to about 221° C. (about 400° F. to about 430°F.), while the temperature of the top platen ranged from about 227° C.to about 243° C. (about 440° F. to about 470° F.).

Procedure for Testing Breaking Strength:

-   -   Equipment: 5500 R Instron machine    -   Immediately prior to testing, each shell bone was removed from        is plastic bag and its weight and thickness recorded.

Weathering Procedure for Shell Bones:

-   -   16 hours weathering in a pre-heated humidity chamber (65° C.,        95% relative humidity)    -   upon removal shell bones were sealed in individual plastic        storage bags and taken immediately for testing.

Procedure for Measuring Gel Time:

A small amount of binder (2.0 ml) is added to the centre of a hot plateset to 150° C. and a stop watch is started. The binder is worked with aspatula until it is possible to draw the sample into a long string. Thetime taken from the addition of the binder to the string formation isthe gel time.

Binder Formulations Tested—Inorganic Acid Precursors Compared withCitric Acid:

Test ref: Binder formulation (by dry weight) A 85% DMH + 15% CA + 4.8%NH4OH + 0.3% ISI0200 B 90% DMH + 10% AmSO4 + 4.8% NH4OH + 0.3% ISI0200 C85% DMH + 15% AmSO4 + 4.8% NH4OH + 0.3% ISI0200 D 80% DMH + 20% AmSO4 +4.8% NH4OH + 0.3% ISI0200 E 90% DMH + 10% AmPO4 + 4.8% NH4OH + 0.3%ISI0200 F 85% DMH + 15% AmPO4 + 4.8% NH4OH + 0.3% ISI0200 G 80% DMH +20% AmPO4 + 4.8% NH4OH + 0.3% ISI0200

Binder Formulations Tested—Combined Inorganic Acid Precursor and CitricAcid Compared with Citric Acid Alone and Inorganic Acid Precursor Alone:

Test ref: Binder formulation (by dry weight) H 85% DMH + 15% CA + 4.8%NH4OH + 0.3% ISI0200 I 85% DMH + 10% CA + 5% AmSO4 + 4.8% NH4OH + 0.3%ISI0200 J 85% DMH + 5% CA + 10% AmSO4 + 4.8% NH4OH + 0.3% ISI0200 K 85%DMH + 15% AmSO4 + 4.8% NH4OH + 0.3% ISI0200

Key:

DMH=Dextrose monohydrate

CA=citric acid

NH4OH=ammonium hydroxide

ISIO200=silane

AmSO4=ammonium sulphate

AmPO4=ammonium phosphate

Test Results—Inorganic Acid Precursors Compared with Citric Acid:

Loss in pH of binder Dry Weathered breaking Gel time solution breakingbreaking strength of binder just before strength strength from weath-solution mixing with Test ref (MN/m²) (MN/m²) ering/% (s) beads A 1.4551.567 −7.70 343 9.54 B 1.271 0.895 29.57 280 10.28 C 1.550 0.856 44.79362 10.24 D 1.877 1.156 38.39 327 10.13 E 1.499 1.069 28.68 356 10.18 F1.281 0.848 33.82 334 9.99 G 1.123 0.801 28.74 287 9.73

Test Results—Combined Inorganic Acid Precursor and Citric Acid Comparedwith Citric Acid Alone and Inorganic Acid Precursor Alone:

Loss in pH of binder Dry Weathered breaking Gel time solution breakingbreaking strength of binder just before strength strength from weath-solution mixing with Test ref (MN/m²) (MN/m²) ering/% (s) beads H 1.691.50 11.32 363 9.39 I 1.50 1.18 21.37 341 9.71 J 1.21 1.05 13.19 3759.99 K 1.47 1.02 30.33 376 9.97

Results from tests carried out together (test A to G were carried out inone session and tests H to K carried out during another session) providea useful indication of results relative to other results obtained duringthe same test session. It may not be reliable to compare tests resultsfrom different test sessions.

First Comparative Testing on Insulation Product:

Comparative Testing of Binder Systems on a Mineral Fibre InsulationProduct Gave the Following Results:

Binder tested Description Formulation PF1 Comparative example - Resin,Urea, Lignin, standard phenol Ammonia, Silane formaldehyde binder AC1Comparative example - Dextrose 85% Citric Acid 15% ammonium citratebased Ammonia 4.8% Silane 0.3% binder Ex1 Example 1 of the Dextrose 85%Ammonium present invention Sulphate 15% Ammonia 4.8% Silane 0.3%

Product used glass wool fibre insulation product, nominal density 16 fortest: kg/m³, nominal thickness 75 mm, nominal width 455 mm

Binder Content of Test Product LOI (Loss on Ignition) % Weight:

Binder Mean LOI PF1 6.22% AC1 6.91% Ex1 6.78%

Drape Test (Mean Average in Mm Measured after the Periods Specified):

Binder Day 1 Week 1 Week 3 Week 6 PF1 55 68 60 71 AC1 83 99 80 72 Ex1 6676 66 75

Thickness (Mean Average in Mm Measured after the Periods Specified inAccordance with British Standard BS EN 823:1995)

Binder Day 1 Week 1 Week 3 Week 6 PF1 76.4 75.1 75.1 75.2 AC1 75.3 73.672.5 74 Ex1 76 76.7 74.9 74.3

Density (Mean Average in Kg/m³ Measured after the Periods Specified)

Binder Day 1 Week 1 Week 3 Week 6 PF1 16.44 16.7 16.35 16.44 AC1 16.6816.41 16.33 16.48 Ex1 16.5 16.9 16.5 16.5

Quantity of Sulphates Present Mg/Kg

Binder Sample 1 Sample 2 AC1 240 240 Ex1 2000 2200

Parting Strength (g/g)

Binder Ordinary Weathered % loss PF1 248 107 56.85 AC1 230 199 13.47 Ex1196 189 3.57

Test Procedures:

Binder Content LOI (Loss on Ignition)

A weighed sample of wool plus binder is placed in a muffle furnace setto 550° C. After a set time the wool is removed from the furnace, placedin a desiccator to cool and re-weighed. The weight loss is expressed asa percentage of the original sample weight and is known as the bindercontent or Loss On Ignition (LOI).

Drape Test

A single batt (or slab) is placed across two poles (each 500 mm long, 20mm diameter) set into a wall 1 metre apart. The degree of sag in thecentre of the batt is recorded. This is repeated for all of the batts ina pack and for several packs. Packs are measured at set points over aperiod of time to determine the long term effects of compression on thebatts.

Density: Measured for the Samples Subjected to the Drape Test

Quantity of sulphates present: leaching test for granular wastes inwater with eluate analysis according to British standard BS EN 12457-2at L/S10

Parting Strength

The parting strength is expressed in grams/gram being the total breakingload of six test specimens divided by their total weight.

The test is carried out on mineral fibre mats as received for testing(Ordinary Parting Strength) and after an accelerated weathering test asexplained below (Weathered Parting Strength).

A first set of six samples of the form and dimensions shown in FIG. 1are cut from the mineral fibre mat to be tested. The dimensions are:

r: radius 12.7 mm;

DC: distance between centres 44.5 mm;

a: 25.4 mm;

b: 121 mm.

The long axis of the samples should be parallel to the conveyordirection and the samples should be taken across the full width of themineral mat. A second set of six samples is then taken in the same way.

The total weight of the first group of six samples W1 in grams isrecorded.

The total weight of the second group of six samples W2 in grams isrecorded; these samples are then placed in a preheated autoclave andconditioned on a wire mesh shelf away from the bottom of the chamberunder wet steam at 35 kN/m² for one hour. They are then removed, driedin an oven at 100° C. for five minutes and tested immediately forparting strength.

To test the parting strength, each sample is mounted in turn on the jawsof a 5500 Instron tensile strength machine and the maximum breaking loadin grams or Newtons is recorded.

If the breaking load is measured in Newtons it is converted to grams bymultiplying it by 101.9. Six results in grams are obtained for each setof samples: G1 G2 G3 G4 G5 and G6 for the first set of samples and G7 G8G9 G10 G11 and G12 for the second set of samples.

The Ordinary Parting Strength is calculated from the first set ofsamples using the formula Ordinary Parting Strength=(G1+G2+G3+G4+G5+G6)/W1.

The Weathered Parting Strength is calculated from the second set ofsamples using the formula Weathered PartingStrength=(G7+G8+G9+G10+G11+G12)/W2.

Second Comparative Testing on Insulation Product:

Product used glass wool fibre insulation product, nominal density 7.2for test: kg/m³, nominal thickness 159 mm

Samples: The Following Samples of Fibreglass Batts were Tested:

Target binder content (LOI) Example Binder Description for product PF2standard phenol formaldehyde binder 4.5% of Resin, Urea, Ammonia, Silane2.1 Dextrose 85% Ammonium Sulphate 15% 4.5% Silane 0.3% (10.6% solids inbinder solution) 2.2 Dextrose 85% Ammonium Sulphate 15% 4.5% Silane 0.3%Norjohn oil (11.4% solids in binder solution) 2.3 Dextrose 85% AmmoniumSulphate 15% 4.5% Silane 0.3%, 2.4% NH3 (10.6% solids in bindersolution) 2.4 Dextrose 85% Ammonium Sulphate 15% 6.0% Silane 0.3%, 2.4%NH3 (10.6% solids in binder solution)

Results

PF2 2.1 2.2 2.3 2.4 Recovery 158 mm 157 mm 163 mm 160 mm 166 mmRecovery. % nominal 99.4% 99.0% 102.8% 100.6% 104.8% Parting Strength190.8 g/g 131.7 g/g 146.7 g/g 159.9 g/g 143.9 g/g (ASTM C-686) Partingstrength after 145.9 g/g 100.0 g/g 110.3 g/g 124.9 g/g 114.3 g/gweathering (ASTM C-686 following conditioning for 7 days at 90° F., 90%relative humidity)

1. A method of manufacturing a mineral fibre thermal insulation productcomprising the sequential steps of: forming mineral fibres from a moltenmineral mixture; spraying a substantially formaldehyde free bindersolution on to the mineral fibres, the binder solution comprising: areducing sugar, an acid precursor derivable from an inorganic salt and asource of nitrogen; collecting the mineral fibres to which the bindersolution has been applied to form a batt of mineral fibres; and curingthe batt comprising the mineral fibres and the binder by passing thebatt through a curing oven so as to provide a bait of mineral fibresheld together by a substantially water insoluble cured binder. 2.-44.(canceled)
 45. The method of claim 1 comprising at least one of thefollowing features: in which wash water is sprayed on to the mineralfibres between their formation and their collection to form a batt, atleast a part of the wash water having been sprayed on mineral fibres andsubsequently returned to a wash water system to be reused as wash water.in which the binder solution is sprayed on to the mineral fibres whenthe mineral fibres are at a temperature of between 30° C. and 150° C. inwhich the binder solution has a pH of greater than 7 when sprayed on tothe mineral fibres.
 46. The method of claim 1 in which curing of thebinder is carried out by passing the batt through at least one zone of acuring oven at a temperature within the range 230° C.-300° C. with anoven residence time in the range 30 seconds to 20 minutes.
 47. Themethod of claim 1 comprising at least one of the following features: inwhich the acid precursor makes up between 5% and 25% by dry weight ofthe binder solution. in which the acid precursor of the binder solutionderivable from an inorganic salt comprises an ammonium salt. in whichthe acid precursor of the binder solution derivable from an inorganicsalt comprises an ammonium salt and in which the inorganic ammonium saltmakes up between 5% and 25% by dry weight of the binder solution. 48.The method of claim 1 comprising at least one of the following features:in which the acid precursor derivable from an inorganic salt of thebinder solution comprises a species selected from the group consistingof sulphates, phosphates, nitrates and carbonates. in which the reducingsugar of the binder solution has a dextrose equivalent value of at least0.85. in which the reducing sugar of the binder solution consistsessentially of dextrose. in which the binder solution comprises asilicon containing compound.
 49. The method of claim 1 in which thebinder solution comprises a material selected from the group consistingof a polycarboxylic acid, a salt of a polycarboxylic acid, an anhydrideof a polycarboxylic acid.
 50. The method of claim 1 comprising at leastone of the following features: in which the binder solution consistsessentially of an aqueous solution of: a reducing sugar; at least oneacid precursor derivable from an ammonium salt selected from the groupconsisting of ammonium sulphate salts, ammonium phosphate salts, andammonium carbonate salts; and, optionally, excess ammonia. in which thebinder solution consists essentially of an aqueous solution of: areducing sugar; at least one acid precursor derivable from an ammoniumsalt selected from the group consisting of ammonium sulphate salts andammonium phosphate salts; and, optionally, excess ammonia, the bindersolution having a pH which, in its conditions of use, preventsprecipitation of sulphates or phosphates. in which the binder solutionconsists essentially of an aqueous solution of: a reducing sugar; anacid precursor derivable from an ammonium salt; a carboxylic acid or aprecursor thereof; and, optionally, excess ammonia.
 51. The method ofclaim 1 comprising at least one of the following features: in which thebinder solution when sprayed on to the mineral fibres comprises at least5% solids. in which the binder solution when sprayed on to the mineralfibres comprises less than 50% solids. in which the ratio by dry weightof reducing sugar to inorganic acid precursor expressed as (dry weightof reducing sugar/dry weight of inorganic acid precursor) is in therange 2.5 to
 13. in which the binder solution comprises between 0.1% and1% of a silane or silicon-containing coupling agent calculated asdissolved binder solids.
 52. The method of claim 1 comprising one of thefollowing features: in which the thermal insulation product has athermal conductivity λ in the range 0.02 W/mK to 0.05 W/mK. in which thethermal insulation product comprises glass wool fibres and has a densityin the range of 8 to 50 kg/m³. in which the thermal insulation productcomprises stone wool fibres and has a density in the range of 25 to 180kg/m³.
 53. A mineral fibre thermal insulation product comprising mineralfibres and a binder, in which the binder is substantially formaldehydefree and comprises a reducing sugar, an acid precursor derivable from aninorganic salt and a source of nitrogen.
 54. The mineral fibre thermalinsulation product of claim 53 comprising at least one of the followingfeatures: in which the binder has a pH of greater than 6 when dissolvedin water. in which the acid precursor of the binder derivable from aninorganic salt comprises an ammonium salt. in which the acid precursorderivable from an inorganic salt of the binder comprises a speciesselected from the group consisting of sulphates, phosphates, nitratesand carbonates.
 55. The mineral fibre thermal insulation product ofclaim 53 comprising at least one of the following features: in which thereducing sugar of the binder has a dextrose equivalent value of at least0.85. in which the reducing sugar of the binder consists essentially ofdextrose.
 56. The mineral fibre thermal insulation product of claim 53comprising at least one of the following features: in which the bindercomprises a silicon containing compound. in which the binder comprises amaterial selected from the group consisting of a polycarboxylic acid, asalt of a polycarboxylic acid, an anhydride of a polycarboxylic acid.57. The mineral fibre thermal insulation product of claim 53 comprisingat least one of the following features: in which the binder consistsessentially of a reducing sugar; at least one acid precursor derivablefrom an ammonium salt selected from the group consisting of ammoniumsulphate salts, ammonium phosphate salts, and ammonium carbonate salts;and, optionally, excess ammonia. in which the binder consistsessentially of a reducing sugar, an acid precursor derivable from anammonium salt, a carboxylic acid or a precursor thereof and, optionally,excess ammonia.
 58. The mineral fibre thermal insulation product ofclaim 53 comprising at least one of the following features: in which theratio by dry weight of reducing sugar to inorganic acid precursorexpressed as (dry weight of reducing sugar/dry weight of inorganic acidprecursor) is in the range 2.5 to
 13. in which the binder comprisesbetween 0.1% and 1% of a silane or silicon-containing coupling agentcalculated as binder solids. in which the binder comprisesglucosylamine.
 59. A mineral fibre thermal insulation product obtainableby thermally curing a product in accordance with claim
 53. 60. A mineralfibre thermal insulation product comprising mineral fibres and a binder,in which the binder is substantially formaldehyde free and comprisesMaillard reaction products and in which the insulation product comprisesmore than 500 mg/kg of species selected from the group consisting ofsulphates, phosphates, nitrates and carbonates.
 61. The mineral fibrethermal insulation product of claim 60 comprising one of the followingfeatures: in which the species selected from the group consisting ofsulphates, phosphates, nitrates and carbonates is derived essentiallyfrom binder precursors. in which the Maillard reaction products comprisemelanoidins.
 62. The mineral fibre thermal insulation product of claim60 comprising one of the following features: in which the thermalinsulation product has a thermal conductivity λ in the range 0.02 W/mKto 0.05 W/mK. in which the thermal insulation product comprises glasswool fibres and has a density in the range of 8 to 50 kg/m³. in whichthe thermal insulation product comprises stone wool fibres and has adensity in the range of 25 to 180 kg/m³. in which the thermal insulationproduct comprises between 1% and 20% binder by dry weight.